In earlier generations, most people married and they remained married to the same person for life. Yet, that kind of marital stability may be artificial. We are moving towards a future of increasingly fragile marriages. So what does it take for a marriage that goes the distance?

Modern marriage is not forever in the sense that there is only gambler’s odds that any union will endure. Increased divorce is just one index of marital weakness. First marriage is delayed by about five years in the U.S. compared to a century ago. Marriage is being avoided entirely by more people.

Even the primary function of marriage—raising children—is no longer marital. In countries such as Norway, Sweden, Estonia, and Slovenia, the majority of children are now raised outside wedlock (1). One reason is that women today are more economically independent and labor force participation predicts out of wedlock births.

Lifetime marriage is recent

Swans may mate for life but permanent marriage is not a pan human trait. Lifelong marriage was common in agricultural societies throughout recorded history. Yet, hunter-gatherer marriages that came before seem to have been quite unstable based on anthropological research (2).

Marriage for life arises in societies where much property is inherited. This phenomenon is illustrated by subsistence farmers where ownership of land is a guarantee of food in the future. In such peasant societies, land ownership is essential for marriage: the farm is equivalent to a blackbird’s breeding territory.

Some farms are better than others and parents of daughters competed amongst each other to place their daughter on a good property, possibly by paying a dowry that she brought with her when she married. Such arrangements involved a lifetime commitment that was hard to break.

Marital separation left wives and children in a particularly untenable situation without a home or livelihood. Hence the phenomenon of zero divorce rates in some agricultural countries. Marriage in those places is like a jail built from public commitment. Stable marriages may not always be happy ones.

In hunter-gatherer societies that lacked inherited property, marriages were easier to dissolve. The bond associated with their marriage is believed to last for long enough to raise a single child. This phenomenon helps to make sense of the fact that modern marriages ending in divorce typically last about seven years (3).

Evidently, we are emotionally equipped to stick with a mate long enough to raise a child to an age when they could walk unaided for the several miles dividing temporary encampments associated with the roaming lifestyle of hunter-gatherers and also collect a lot of their own food and feed themselves independently. The sexual bond is thus analogous to the pair bond that keeps bird pairs together throughout a breeding season.

Of human bonding

Of course, this analogy raises the further question of how any marriages get to last for life. There are many plausible explanations. The most obvious involves the presence of multiple children in the home. Each new child is like another breeding season that draws the couple together anew.

This might seem like a rather sentimental claim, especially when you consider that parents of young children are often harried and unhappy—perpetually tired, sleep-deprived, and financially stretched. Yet, the reality of such sacrifices is that they draw couples together through some relationship magic that psychologists do not yet fully comprehend. Of course it is also true that many such parents could not afford to get divorced.

We may be in the dark about the psychological mechanism that draw parents together but the evidence that they do is overwhelmingly strong. Childless couples are at a high risk of splitting up whereas parents of five children almost never do (3). However unhappy they might be, it seems that their commitment to the children unites them with bonds of steel. Fathers are particularly involved with male children and the birth of a son protects a couple from divorce more than the birth of a daughter does (4).

While parents keep producing young children, their marriages are generally very safe helping explain why marriages are so unstable in the modern world with its very low fertility. Couples today lack the adhesive power of multiple young dependent children. Of course women are also more economically independent of men in a low-fertility world where contraception is widely used.

Even after the last born is raised past childhood, the birth of grandchildren may help couples to stay together because the shared experience of being grandparents combines many of the attractions of parenthood with almost none of the disadvantages. .

In societies with high divorce rates, some couples are less likely to split up than others. Personality matters and agreeable people are much better at negotiating compromises so that their unions may weather conflict.

Unions are also more stable if the partners have more in common in respect to education, religion, politics, and so forth. This explains why married couples are often closely matched in these traits.

Otherwise, lifelong marriage is assured for women who marry a subsistence farmer, fill the house with male children, and stay out of the paid work force.


1. Eurostat (2011/2012/2013). Marriage and divorce statistics. Accessed at: on 7/17 2013.

2. Shostak, M. (1981). Nisa: The life and words of a !Kung woman. Cambridge, MA Harvard University Press.

3. Barber, N. (2002). The science of romance: Secrets of the sexual brain. Amherst, NY: Prometheus.

4. Mammen, K. (2008). The effect of children’s gender on living arrangements and child support. The American Economic Review, 98, 408-412.

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